Question

Lets say you have an program like this:

$info = array(
    'username'=>'jeff',
    'password'=>'kay'
);

function authenticate($user, $pass) {
    if($user == $info['username'] && $pass == $info['password']) {
        return true;
    }
    return false;
}

This code won’t work because the $info array isn’t in authenticate()‘s scope. You would have to pass $info as a parameter of authenticate() like so:

function authenticate($info, $user, $pass) { // ... }

This feels wrong to me.

I could certainly add global $info; inside of authenticate but that feels even more wrong. What is best practice for structuring a PHP program to avoid scope issues like this? You don’t see functions requiring you to pass in the ‘global’ object in modern code it seems like. How do I avoid unnecessary function arguments?

Answer 1

Most people do not notice, but this is actually a very good question.

Many other languages (especially functional ones) have lexical scope. With PHP 5.3 lambdas you get that capability, but only within lambdas. Let me show you what I mean:

$info = array(
    'username'=>'jeff',
    'password'=>'kay'
);

$authenticate = function ($user, $pass) use ($info) {
    if ($user == $info['username'] && $pass == $info['password']) {
        return true;
    }
    return false;
}

if ($authenticate($_POST['username'], $_POST['password'])) {
    // use authenticated
}

With the use you can import variables from the outer scope, but it only works for anonymous functions. It really depends on what kind of style and framework you’re coding in/with.

If you don’t want to define these inline (since you must assign them to variables, which is not so nice), I’d suggest you go with your instincts, so pass $info into authenticate or make $info an instance variable of the class that authenticate belongs to.